As a new type of solid illumination source and environmentally friendly light source, a light-emitting diode (LED) has the characteristics of small size, low power consumption, environmental protection, long service life, high brightness, low heat and colorfulness, etc., and has a wide range of applications in outdoor lighting, commercial lighting, decorative engineering and other fields.
At present, most of the industrialized LEDs use sapphire as the substrate; however, since the sapphire itself is not electrically conductive, the current flow direction of the prepared LED chip is horizontal, that is, the prepared LED chip is a horizontal structure LED. The horizontal structure LED has been widely used due to its simple process and industrial scale. However, due to the bottleneck suppression effect on the current in the horizontal direction, the light effect of the horizontal structure LED is difficult to be improved. The corresponding vertical structure solves the problem of current distribution. The existing vertical structure has a vertical structure based on a sapphire substrate. However, a vertical structure LED chip on the sapphire substrate needs to be subjected to lifting of the substrate by laser, which not only increases the cost but also has a complicated process, often leading to a decrease in yield; besides, its application is often limited by various patents. Therefore, it is urgent to find a new type of substrate to prepare vertical structure LED chips.